1. Field of Invention
The current invention concerns a biocompatible cell-support matrix having narrowly defined and uniformly vertically and non-randomly organized porosity and a pore density and a method for preparation thereof. In particular, the invention concerns a biocompatible cell-support matrix or support substrate having substantially the same size pores said matrix or substrate providing a support structure for live-cell suspension. The matrix has vertically non-randomly oriented open pores of substantially homogeneous pore size and narrowly defined diameter.
The support matrix seeded with the chondrocyte suspension is suitable for initiation of growth and de novo formation of hyaline or hyaline-like cartilage in vitro and in vivo as well as for preparation of cellular or acellular implants for implantation into articular cartilage in situ.
The invention additionally concerns a collagen-matrix composite system comprising of said support matrix seeded with chondrocyte suspension, said system being capable of induction of hyaline or hyaline-like cartilage from chondrocytes in vitro or in vivo when introduced into the articular cartilage in situ.
2. Background and Related Disclosures
Collagen matrices for use as an implant for repair of cartilage defects and injuries are known in the art. Of particular interest is a honeycomb structure developed by Koken Company, Ltd., Tokyo, Japan, under the trade name Honeycomb Sponge, described in the Japanese patent JP3170693. Other patents related to the current subject disclose collagen-based substrate for tissue engineering (U.S. Pat. No. 6,790,454) collagen/polysaccharide bilayer matrix (U.S. Pat. No. 6,773,723), collagen/polysaccharide bilayer matrix (U.S. Pat. No. 6,896,904), matrix for tissue engineering formed of hyaluronic acid and hydrolyzed collagen (U.S. Pat. No. 6,737,072), method for making a porous matrix particle (U.S. Pat. No. 5,629,191) method for making porous biodegradable polymers (U.S. Pat. No. 6,673,286), process for growing tissue in a macroporous polymer scaffold (U.S. Pat. No. 6,875,442), method for preserving porosity in porous materials (U.S. Pat. No. 4,522,753), method for preparation of collagen-glycosaminoglycan composite materials (U.S. Pat. No. 4,448,718), procedures for preparing composite materials from collagen and glycosaminoglycan (U.S. Pat. No. 4,350,629) and a crosslinked collagen-mucopolysaccharide composite materials (U.S. Pat. No. 4,280,954).
However, many of the above disclosed structures have uncontrolled parameters such as uneven and uncontrolled porosity, uneven density of pores, uneven sizes of the pores and random distribution of pores within the support matrix. Such uncontrolled parameters lead to structures that are sterically unstable to provide support for cartilage matrix producing cells as these structures easily collapse upon contact with a solution or suspension containing cartilage producing cells.
There is, therefore, a need for a more uniform and sterically stable support matrix preferably prepared from a biocompatible material, such as collagen, wherein said matrix has narrowly defined size and density of pores and the pores are uniformly distributed, vertically oriented and non-randomly organized.
It is, therefore, a primary object of this invention to provide a sterically stable biocompatible, preferably collagen based matrix, having properties enabling chondrocyte attachment in numbers needed for induction and formation of hyaline or hyaline-like cartilage.
The current invention provides such matrix and/or a method for fabrication thereof by providing a sterically stable and biocompatible matrix, preferably made of Type I collagen, having narrowly defined pore sizes and density with said pores organized vertically wherein said matrix permits seeding and attachment of chondrocytes suspended in collagen, gel, sol-gel or hydrogel that gels at the body temperature, in sufficiently high numbers to induce formation of new hyaline or hyaline-like cartilage. The matrix according to the invention has a substantially narrowly defined pore size in diameter and pore density in vertically organized manner that creates an apical (top or synovial) or basal (bottom or bone) surface to the implant where the sizes and diameters of the pores on both the apical or basal surface are substantially the same. The gel system according to the invention provides conditions for a sterically-enhanced enablement of chondrocytes to produce extracellular matrix comprising glycosaminoglycan and Type II collagen and its deposition within said matrix in ratios characteristic for normal healthy articular hyaline cartilage.
All patents, patent applications and publications cited herein are hereby incorporated by reference.